Bees are dying. Three-quarters of the world's
250,000 flowering plants, including many fruits and vegetables, require
pollination to reproduce.

Who is
going to pollinate my crabapples and apples?: Honeybee Decline Concerns
Congress

No bees, no
crops. For many reasons, the U.S. honeybee population is declining. The
phenomenon now called Colony Collapse Disorder (CCD) quickly spread across
the nation and has now drawn the attention of the U.S. Congress.
Agricultural crops pollinated by honeybees accounts for about one-third of
the U.S. diet. The monetary value of honey bees as commercial pollinators in
the United States is estimated at about $15 billion annually. Worldwide,
three-quarters of all flowering plants require pollination to reproduce.
Among food crops considered to be from 90-100 percent dependent on bee
pollination are almonds, apples, avocados, blueberries, cranberries,
cherries, kiwi fruit, macadamia nuts, asparagus, broccoli, carrots,
cauliflower, celery, cucumbers, onions, legume seeds, pumpkins, squash, and
sunflowers. Other important crops needing pollination, include many fruits
and citrus fruits, peanuts, cotton and soybeans.

While
honeybee declines have come and gone in the past, Colony Collapse Disorder
is unsettlingly different. In it's March 26, 2007 report
Recent Honeybee
Colony Declines (link above), the Congressional Research Service found that current bee colony losses differ from past situations in that:

colony losses are occurring mostly because bees are
failing to return to the hive (a behavior uncharacteristic of bees),

bee colony losses have been rapid,

colony losses are occurring in large numbers, and

the reason the losses are occurring remains
largely unknown.

The reason for honey bee CCD
may be a combination of multiple factors, such as disease, mite infestations
in hives, insecticide use in hives, and insecticides in the foraging
environment. One honey bee researcher in Florida are blaming the current
bout of CCD on the use of imidacloprid (Merit). Imidacloprid affects bee
behavior, orientation, grooming, and nest activities according to 100's of
published studies.

Our research
demonstrates that imidacloprid is translocated to nectar and kills foraging
biocontrol agents, such as: green lacewings, parasitoids, and lady beetles.

This pest was in the
March 2006 newsletter, but you might also have rose stem borer; damage can
look very much alike, so see the next entry!!

Time: May, June

Hosts:
Roses

Mossy
rose galls are caused by a cynipid gall wasp. They
are becoming common on Rugosa cultivars. The presence of these insects is
indicated by the formation of spherical, golf ball-size, spiny galls on the
canes of host plants. The development of these galls is stimulated in the
spring by newly hatched larvae. The galls encase the larvae until adult
wasps emerge the following spring. The galls are unsightly and alter the
plant's shape. They also stress the host plant, behaving like nutrient
sinks, drawing nutrients away from the rest of the plant. Large numbers of
galls can result in death of the plant.

The most
effective control is physical removal and disposal of galls in autumn after
leaves have dropped and galls are visible. It is important to dispose of all
galls since even a single missed gall can produce and reintroduce 30 to 40
mature wasps to the garden the following spring. Imidacloprid soil
applications may be effective.

Another pest of rose canes is the
stem dieback caused by the flatheaded borer,
Agrilus aurichalceus. Rose canes are damaged
when larvae tunnel in a spiral fashion beneath the bark, girdling and
killing the canes (figures below). Their presence is indicated when a cane
dies above the point of borer tunneling. Leaves on the infected cane turn
brown as they die, creating a "flag" among healthy, green-leaved canes. On
close observation, a swelling or gall on the infected cane can be seen below
the dead tissue, indicating where the borer's tunneling occurred. The gall
formation weakens canes and it is common to see infected canes broken off by
wind. The quickest and most effective control is removal and disposal of
infected canes in fall.
Imidacloprid can be used in summer to kill borers.

Cooley
spruce gall adelgid is a native pest. Galls can be
found on Colorado blue spruce and Engelman fir. This aphid-like insect may
use Douglas fir as an alternate host, but galls will not be found on this
species.

Damage
symptoms: Cone-shaped galls occur at the tips of
the new growth of host plants. The galls turn brown in summer.

Monitoring and control of these two pests is the same.

Eggs hatch
when common lilac blooms in the first two weeks of May (Herms). Use sticky
traps in late summer to detect flying adults. Look in late winter at the
base of needles for wax-covered nymphs overwintering. Look in spring for
galls forming. Look for white covered Cooley spruce adelgid adults on
Douglas-fir.

Physical
control: Prune out green galls in spring or early
summer and destroy them. For aesthetics, prune out remaining brown galls in
summer.

Chemical
control:
carbaryl,
chlorpyrifos (nursery only),
deltamethrin. Sprays can be used to kill overwintering
females in late fall. It is difficult for pesticides to penetrate waxy
covering on females on Douglas-fir. Spray the underside of new branches.

Hosts:
prefers gray and paper birch, but also feeds on black, European white, river
and yellow birch

Damage
symptoms: Larvae feeding singly on tissue between
leaf surfaces cause small kidney-shaped mines. As larvae grow larger these
areas coalesce to brown, irregular, wrinkled blotches. Heavy infestations
can cause browning of all the leaves. Affected trees may be killed but are
more commonly weakened, leading to attack by other insects.

Monitoring: Adults emerge when Eastern red bud and
crabapple bloom in late April to early May (Herms). Look for adults on new
leaves. Yellow sticky traps can be used to monitor adult populations for
each generation. Look for the brown kidney-shaped marks that indicate larval
mine formation.

Cultural
control: Replace susceptible species with more
resistant ones, such as Betula nigra,river birch.

Chemical
control: Soil applied systemic insecticides, such
as imidacloprid, should be applied to the soil in the fall to kill adult and
larval birch leafminer the following spring. Soil applied systemic
insecticides, such as disyston, should be applied to the soil in spring.

Biological control: The ichneumonid wasps
Lathrolestes nigricolis and Grypocentrus albipes are considered
themost important natural enemies. These were introducedinto
the Northeast from Europe, but have not spread tothe Midwest (Guevremont
and Quednau 1977). Inaddition, 17 parasitoids attacking native
leafminers alsoattack this introduced pest (Cheng and LeRoux 1969).

Monitoring: Look in June for 3 mm long, D-shaped
exit holes in bark. Adults emerge when black locust and multiflora rose
bloom in late May to early June (Herms). Look for terminal dieback on
susceptible birches.

Chemical
control: Spray bark within week of first adult
emergence. Imidacloprid can be applied to the soil or injected in early
spring to kill bronze birch borer larvae. Mauget with bidrin is also
effective.

Biological control: Egg parasitism by Thysanus
and Coccidencyrtus
spp. was reported to be 50% in New Jersey (Barter 1957). It was lower (7%)
in Pennsylvania on European white birches that were planted to reforest
strip mines, and the parasitoids that were responsible were mostly the
encyrtids Avertianella sp. and Ooencyrtus sp. (Loerch and
Cameron 1983). Larval parasitism rates reached about 18% in New Jersey and
Pennsylvania (Barter 1957). Important larval parasitoids in New Jersey
include the chalcidid Phasganophora sulcata, the braconid
Atanycolus charus, and the eulophid, Tetrastichus sp. in
Pennsylvania.

Life history: Native pest. When you get several
days that are sunny and the temperatures reach the mid-60 F, females emerge
from litter under trees and crawl to the upper parts of their host trees.
The female weevil chews new holes at the leader tip to insert her eggs just
under the bark. New adults emerge from July to September feed on branches in
late summer and fall. They often make holes by the base of the trees and
cause sap flow.

Insecticide timing: Nursery and
landscape: Astro (a long lasting permethrin, pyrethroid formulation) or
Onyx
(long lasting bifenthrin, pyrethroid) can be applied to the top leader of
trees that are likely to be attacked. Retreatment is needed every 14 to 20
days until June.

Christmas trees: Metasystox-R or dimethoate two times, once
in early to May and again about three weeks later! While MSR can still be
used by professional applicators and dimethoate is only registered for tree
plantations (including), this leaves much to be desired for protecting
residential trees.

Life history: Native pest. Adults feed on bark
near the ground in early spring and begin egg laying. They later move to and
feed in the upper crown branches. Eggs are deposited throughout the summer.
Development may take more than one year. Larvae feed just below the soil
surface on the inner bark and sapwood of stems and large roots. This
feeding girdles the bark and restricts the transport of nutrients, thus
weakening the tree and retarding growth. Eventually the tree's needles
yellow and turn a deep reddish brown. A swollen trunk at ground line and
darkened, pitch-infiltrated soil around the root collar indicate an
infestation. Chronically damaged trees are easily blown over.

Monitoring: Carefully monitor small
trees (2.5 to 10 cm in diameter) and trees growing in poor soil, as these are
usually most severely damaged. Look for white pitch flow on bark and into
the soil around the root collar during the growing season. Search debris
under trees to look for adults. Cut into the bark of infested root crowns to
detect larvae.

Physical control: Prune away lower
branches and expose soil to sun at the base of the tree.

Insecticide timing: Use a
persistent registered insecticide to drench the root collar of infested
trees, such as Onyx (bifenthrin),
chlorpyrifos,
permethrin. Research indicates that
this will control parent adults hiding at the base of the tree, and newly
emerging adults. Apply cover sprays in mid-May (about 300 to 350 degree days
[base 50]) and again in mid-August (1200 to 1400 degree days [base 50]) to
control adult weevils feeding on shoots.

Time:
All times of the year, but particularly during winter and early spring when
greenhouses are drier

Hosts: over 300 woody and herbaceous species

Twospotted spider mites can occur at any time of the year in the greenhouse;
however, populations are more severe in dry conditions, particularly in
winter and early spring. They attack over 300 host plants; both woody and
herbaceous plants are at risk.

Adults
are 0.4 mm long and have eight legs. They are easily recognized by the two
to four black spots on the semi-transparent body. Eggs are round and
transparent. Larvae have six legs, and nymphs have eight.

Twospotted spider mites damage plants by inserting their chelicerae into
plant tissue and sucking the contents of leaf cells. This causes
characteristic stippling on the leaves. In heavy infestations, the mites
produce extensive webbing over plants and can cause leaf drop. Monitor for
mites by looking for damage and examining the undersides of leaves for mites
and eggs. Beat plants with a stick and collect mites and eggs over a white
cloth. Mites mature in 5 to 20 days depending on temperature and females
lay over 100 eggs during their lives.

Management: Small populations of twospotted spider
mites can be managed with oils, soaps, or biological control agents. Washing
leaves with water may dislodge some of the mites, and increasing the humidity
in the greenhouse will make a less favorable habitat. In heavy infestations,
miticides should be used. Rotate between classes of
miticides to prevent spider mites from becoming resistant to the miticides.

Darkwinged fungus gnats are small flies
that commonly occur in the greenhouse. Larvae feed on roots of plants and
mature in two weeks. They are white with black head capsules and reach 5.5
mm in length. Adults are small (2.5 mm
long), dark gray to black, with long legs and long, filiform antennae. They
live for one week and females can lay up to 150 eggs on the soil surface
during that time. Adults are weak fliers and do not feed.

Fungus gnats are usually considered
nuisance pests, but larvae sometimes vector root rot pathogens to plants.
Monitor for larvae by placing potato slices on the surface of the soil, and
monitor for adults with yellow sticky cards. Wilted plants may indicate the
presence of fungus gnat larvae and root rot.

Thrips feeds on the flowers and foliage by inserting its
modified left mandible into the tissue, and sucking the fluids from cells.
Oviposition and feeding scars reduce the aesthetic quality and marketability
of ornamental plants. These thrips spread tomato spotted wilt (TSWV) and
impatiens necrotic spot viruses (INSV).

Females lay eggs in tender plant tissue. The eggs hatch in 2
to 14 days, depending on temperature. Larvae are found in the protection of
perianth of the flower or within developing terminal foliage. Late in the
second instar they stop feeding and move down the plant to pupate. Thrips
develop through two quiescent, non-feeding pupal stages in the soil, plant
litter or in a protected area on the plant. Adults emerge and resume
feeding on flowers, buds, and terminal foliage. The entire life cycle from
oviposition to adult emergence can take 12 days in hot weather to 44 days in
cool weather.

Management: Rotate classes of
insecticides to prevent resistance. Use blue or yellow sticky cards to
monitor for adults.

Thrips feeds on the flowers and foliage by inserting its
modified left mandible into the tissue, and sucking the fluids from cells.
Oviposition and feeding scars reduce the aesthetic quality and marketability
of ornamental plants. Greenhouse thrips move relatively slowly and rarely
fly. They prefer a cool, shady, and fairly moist atmosphere. Reproduction is
usually by parthenogenesis (laying unfertilized eggs). Under optimum
conditions the time for development is 17 to 20 days for the eggs, about 13
days for the two larval instars, and about 5 days for the prepupal and pupal
stages. The adults can live 7 weeks on plants growing in the greenhouse.
Dark spots of excrement are often noticeable on the leaves and fruit. Pupae are found on leaves.

Life history: Native pests.
Full-grown cutworm larvae are about 1-1/2 inches long When disturbed,
cutworms roll into a ball. Black and variegated cutworms are the most common
pests on home lawns. Black cutworm (three generations per year) does not
overwinter in the upper Midwest. Moths migrate northward from southern
states in early spring and deposit clusters of 10 to 20 eggs on grasses and
weeds. Bronzed cutworms (one generation per year) overwinter as eggs that
hatch in early spring. Fully-grown larvae are present by late April and
pupation occurs during mid-August. Variegated cutworms (one generation per
year) overwinter as partially grown larvae and resume feeding as grasses
start to green. Cutworms feed at night leaving trails that can be seen in
the dew. Cutworms hide during the day in aeration holes or in the thatch.

The
black cutworm
is dark gray to black with a pale stripe down the back, but with few other
distinguishing markings he
variegated cutworm
is grey to brown with an orange lateral stripe and a series of darker
lateral markings with a row of yellow or white dots runs down the middle of
the back. Black cutworms are common on golf courses. Light traps and
pheromone traps can be used to monitor adult activity.
Bronzed cutworms
are dark brown to black on the upper side of the body and paler on the
underside. The upper surface has three narrow yellow stripes and a broad
white-yellow stripe running down each side. The entire body has a
distinctive bronze sheen. Bronzed cutworms are spring and early summer
pests. During the day they hide in the soil or under debris.

Life history: The adults of sod
webworms are called lawn moths. They are light-colored moths, which make
short, erratic, darting flights above the turf and are attracted to lights
at night. When resting they fold their wings back closely against their
bodies, which gives them a very narrow appearance. Also, their heads appear
to have a long snout.

The moths lay their eggs in the lawn. The older larvae are a
dirty white to light brown with darker spots and are about 3/4 inch long
with a black head. The larvae feed at night on grass blades. During the day
the larvae hide in silk-lined tunnels or burrows at or slightly into the
soil surface. Some species damage plant crowns or roots as well as blades.

Two or more generations can occur in Minnesota. Although
webworm adults are commonly seen, larval damage is uncommon in Minnesota.